Today it is well known to use homogenizers within the food processing industry. For instance, within the dairy industry homogenizers are used for dividing fat globules into minor parts in order to obtain a stable fat emulsion against gravity separation. In other words, by homogenizing milk one can avoid that a cream layer is formed on top of the milk product. Other reasons for homogenizing food products are to achieve a more appetizing colour, reduced sensitivity of fat oxidation, more full bodied flavor, improved mouthfeel and better stability of cultured milk products.
Generally a homogenizer can be divided in two main parts, a high pressure pump forming a high pressure and a homogenizing device providing a gap through which the product is forced. Today, most often the high pressure pump is a piston pump with three to five pistons. In order to make sure that unwanted microorganisms are not spread to the product when the pistons are moving back and forth piston seals are used. A common approach is to have at least two piston seals placed apart from each other such that a barrier can be formed between the product, placed on a so-called hygienic side, and non-hygienic parts of the homogenizer, such as crankcase and crankshaft using hydraulic oil, placed on a so-called non-hygienic side.
For example, in non-aseptic homogenizers, i.e. homogenizers placed upstream a heat treatment station, a common approach is to have double piston seals with water provided between the seals to lubricate the pistons. In aseptic homogenizers, i.e. homogenizers placed downstream a heat treatment station, a mixture of hot condensate and steam may be supplied between the seals in order to prevent re-infection.
The homogenizer and the homogenizing process are further described in “Dairy Processing Handbook” published by Tetra Pak, hereby incorporated by reference.
Since it is difficult to keep the hygienic side and the non-hygienic side apart when the pistons are moving back and forth some food producers have decided to use only food graded oils as a precautionary measure. By doing so they reduce the risk of causing health issues, but if the oil finds its way to the product the product properties are nevertheless negatively affected.
For the above mentioned reasons, it is today requested from food producers to make sure that the oil does not end up with the product in order to avoid health issues and product losses.
Further, apart from reducing the risk that oil does not end up with the product it is important that the technical solution is cost efficient both from capital expenditure perspective and operational performance expenditure. In other words, the technical solution should require a reasonable investment cost for the food producer and when running the technical solution the need for utilities should be kept at a low level, and providing service should be possible without increasing operational costs significantly.